


Sin and temptation

by blackcrystaly



Category: Sherlock (TV), Sherlock Holmes & Related Fandoms
Genre: Alternate Universe, Demons, Humor, M/M, PWP, Smut
Language: English
Status: Completed
Published: 2015-01-20
Updated: 2015-01-20
Packaged: 2018-03-08 10:41:03
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,698
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/3206237
Author URL: https://archiveofourown.org/users/blackcrystaly/pseuds/blackcrystaly
Summary: <blockquote class="userstuff">
              <p>Sherlock finally learns of John's true nature.</p>
            </blockquote>





	Sin and temptation

**Author's Note:**

> This story was born because I wanted to try to write something lighter than the stories I have been coming up with lately and to work a bit on humor. Also this is true and unrepentant PWP. 
> 
> As I ever said English isn't my main language so please be kind while pointing at the mistakes you might and surely will find. I'll try to come back several times during the next hours to make little adjustments and to correct some mistakes, but just now you might take into account that it has only gone through the Word corrector.
> 
> The story is being betaed by alexisriversong. All my thanks to her!

Sherlock realized he was in danger once again. He had miscalculated the time it would take for John to catch up with him and now he was being held at gun point by a raving murderer who was about to shoot him without confessing or answering any of the question that his killings had arisen. Somehow it made him remember the cabbie case they had solved so long ago. But this man in front of him had no intention of playing games with him and give time to any rescuer to act.

A moment later, the younger Holmes felt a bullet go through his body and he could feel his black, dense blood begin to spill away. One of his pale hands touched the place where he had been hit and smiled darkly. It had been so long since he had felt this piercing pain…

“ _Sherlock!!!_ ” John yelled his voice full of despair.

The Consulting Detective was about to turn around to reassure his partner, lie to him, tell him he had only been scratched when he noticed that his attacker was about to kill the blond. Sherlock was ready to reach and dispose of the man when he saw Watson change right before his eyes. The former soldier moved with supernatural speed, while emerald green bat-like wings ripped out the back of his clothes in their haste to appear, the Consulting Detective could see medium length horns and an arrowhead like ended tail show up. John grabbed the murderer by the neck and raised him from the ground while his other hand forced the man drop the gun.

“ _You…_ ” He began to say almost hissing and slowly choking the life out of the younger Holmes's attacker.

Sherlock finally reacted.

“John, I’m fine” He whispered softly slowly walking to the other.

Watson turned his head to watch the brunette completely caught of guard. He had seen the bullet go through his partner; it was simply not possible he had survived! His knowledge of human anatomy kicked in and he wondered if maybe the killer had missed a vital organ, but then the younger man might be going into shock or even agonizing without realizing it, and they could be losing precious seconds to save the man's life. With those thoughts in mind, John threw the murderer aside not even caring where or how he landed and turned to Sherlock.

He forced the brunette to lay on the floor and was about to reduce the other man's shirt to shreds with his claws to examine him when the brunette stopped his hands by grabbing Watson's the wrist.

“ _John, I’m fine_ ” He repeated.

“You might be in shock” John contradicted him worriedly, his eyes scanning the thin body, failing to see Sherlock's wound, wondering if he should transport the Consulting Detective to the nearest clinic or if he should intervene... in quite a different way.

Sherlock realized he would have to show Watson what he meant to be believed and with a thought the younger Holmes let his own demonic self appear.

John watched mesmerized as the man he had been living with changed right in front of him. The first thing he noticed were dark, twisted horns at each side of Sherlock’s head, and a moment later a black arrowhead-like ended tail caressed the side of the blond’s cheek.

“Would you let me get up now?” The brunette asked with dark shining eyes.

John helped the other get up from the floor. He could then observe, for the first time, his partner's black, long wings, bat shaped just like his. He stood there for a second, observing them before both men finally turned to the place where the one they had been chasing after had fallen. He apparently looked unconscious, but then Sherlock noticed there was something wrong, and pulled John to his body before the blond could even touch the murderer. Watson looked at him surprised, but then noticed he noticed the detective's eyes fixed at the shadows near the man's limp body.

“It’s okay, Sherlock, I wouldn’t have let Doctor Watson get hurt” A known voice came from somewhere in front of them.

Suddenly a shape began to take form and John could distinguish Mycroft Holmes smiling softly at them. The only detail that revealed his true nature was the red shining eyes. He pointed at the body with the tip of his umbrella.

“He won’t wake up until the cops are here, which will be in…” he consulted his pocket watch “eleven-point-twenty minutes” He said calmly before turning to look at the other two other demons.

Sherlock nodded and the other greeted them before disappearing.

“Why did you stop me, Sherlock?” Watson asked once the older Holmes had vanished.

“The kind of magic Mycroft uses sometimes can evenhurt our kind” He explained before studying the blond still trapped by the waist “You certainly managed to keep a big secret from me, John”

The other blushed visibly.

“It just never came up” He whispered not bothering to move away even when he could heard the police sirens getting closer “you never told me, either” he protested weakly. He had suspected, of course, but when he had seen the man hurt all rational thought had flown from his mind.

“I thought you already knew” He said simply, shrugging his shoulders. It had been painfully obvious from the beginning, his observation powers, his resilience, even his character. How could have John missed it? He had never made any attempt to hide his nature to anyone. John instead… Sherlock had more than once wondered if the former soldier wasn’t an angel, one of Michael’s army maybe sent as a spy.

Watson shook his head. That was such a typical Holmes’ answer, a little nervous laugh escaped his lips.

The brunette looked at him surprised, he realized that the other was still trying to process that he was alive and well, a demon just like him. Also, he noticed that John wasn’t event trying to put some distance between them.

 

“Is it safe to touch him?” Gregory Lestrade’s asked at the pair arriving from behind.

Sherlock turned to look at the silver fox and nodded.

“The spell should have dispelled by now” He answered at last.

The other man ordered his team to handcuff the still unconscious man and take him to NSY. He remained behind. Only then he was finally able to see Doctor Watson who had remained almost concealed by Sherlock’s wing. That alone told the Detective Inspector that things had taken a turn, if for good or evil it was still to be seen. Suddenly, he noticed the blond was showing demonic traits and he found himself genuinely surprised, Greg would have sworn the former soldier was a the player for the other team!

“What happened, Sherlock?” He asked managing to sound professional yet friendly.

“Mister Blomms shoot me when I cornered him” The taller one explained succinctly before frowning “I hate when they refuse to explain the little dark points!”

That phrase made Watson laugh almost hysterically, finally letting go of the worry and the dark thoughts that had overcome him when he had seen the bastard hit Sherlock. His partner, the one he had fallen for the moment they were introduced to each other was at his side, alive and well. He felt giddy with happiness!

The brunette looked at the former soldier his eyes full of worry much like those of the silver haired man.

Suddenly, a strong hand trapped Sherlock by the back of his neck and he was pulled into a heated, unexpected kiss. _John certainly knew how to be daring, but then, he had always known that_ Sherlock thought before letting his own tongue entwine with the other.

Some seconds later a short cough brought the pair to reality.

“Sorry to interrupt, but I suggest you move to Baker Street… even if you are both protected by some of the new laws it’s still indecent behavior” Gregory said well naturedly.

“You are just jealous!” The younger Holmes protested.

“Sherlock!” Watson called out to him in his “bit not good” tone.

“It’s the truth!” The Consulting Detective pressed on, bothered at being interrupted “Just because Mycroft has never even laid a finger on him…”

The blond looked at the other as if he was crazy, then he noticed how much the other’s words were hurting Lestrade and decided that enough was enough.

“Do you really need to hurt one of our few friends?” He asked seriously before moving away from the black winged one “Sorry, Greg…” John offered walking slowly to the other.

The Detective Inspector thought that the doctor certainly made for a beautiful demon and if he wasn’t already smitten with Mycroft Holmes would certainly try to tried to seduce him, not that he thought he had any chance of winning him over Sherlock… or to live too long if he so much as attempted to take the other away from the younger looking man.

“It’s okay” he said calmly “I’ve known Sherlock for quite a long time to know not to to take it terribly personal”

“Well, he was a brat” John continued slowly turning to his more normal self “look, if you want to talk one of these days…” he offered amiably.

Gregory smiled kindly to the other.

“I’ll text you, okay?” He said at last “Now, please, take that idiot of demon you have behind you home and shag him senseless before he makes my life even worst!”

Watson looked at the grey eyed man, caught by surprise before smiling evilly and turning to the younger one who seemed to be silently fuming.

In any other time Sherlock would have already left, but this time he had seen a strange light in Lestrade’s eyes when he had looked at his John and wasn’t going to risk the man seducing Watson away from him when he seemed to be so close to finally have his chosen one for himself. He wouldn't have cared if John was an angel, he had already decided to bring the man over if that was the case, made him one of the fallen. Now that wasn’t a problem anymore and he felt his chances were slightly higher than before.

The blond walked back to the brunette and put one arm around the brunette’s slim waist.

“Do you know how to teleport?” He asked seriously. Not many demons had been able to develop such power since it was too energy consuming, usually it was something they managed to do once they were older. If the other man couldn’t do it they would have to either revert to human form to try and flag a cab although their clothes were pretty much rags and ruins by then or to fly, and since he had been hurt during the war John hadn’t been able to keep on the air for too long. The blasted holy spear had gone through his flesh hard enough to damage him for many years to come.

“Of course I can” The other answered proudly, before closing one of his wings around the John’s slightly smaller frame. A second later both demons had disappeared into thin air leaving behind a crestfallen Lestrade.

 

 

Both demons appeared in Sherlock’s bedroom at 221B. Without losing any time, the taller one pushed his partner on the bed. John smiled sensually and licked his lips invitingly.

“Impatient, aren’t you?” He asked while making himself comfortable on the big mattress, and making his wings and tail disappear in a blink. They were mostly bothersome while in horizontal position unless the furniture had been enchanted for them and somehow he suspected that wouldn’t be something Sherlock had done, considering how little attention he paid to his own body.

The brunette’s eyes shone darkly. This creature in front of him wasn’t the calm and kind Doctor Watson he had come to care for and want for himself, this was a creature of sin and temptation and he felt the need to own him grow even stronger. He also decided to make his wings and tail disappear. There would be time later to bring them into play and with a quick movement he disposed of the rest of his already ruined clothes and crawled on the bed. He insinuated himself between the other man’s legs while his black claws slowly reduced to slices the the rest of Watson's clothes leaving faint pink traces all over the doctor’s tanned skin.

“Sherlock!” John protested half-heartedly since the rough treatment had only made him hotter. He loved to have a partner with such a tight control over his own strength that they could made the play a bit edgier without going into pain.

He grabbed the brunette by the nape once more and pulled him closer for another passionate kiss, their tongues playing a sensual game while trying to conquer the other’s mouth.

“I’ll never get your depths, John” Confessed Sherlock with a smile when they broke the contact.

“It’s only fair” The green eyed replied while turning them around and mounting over the other’s waist his own claws showing as he caressed the man’s heated skin very slowly “since I won’t ever get all of your secrets…” John whispered into Sherlock’s ear before biting the lobe.

He moved to the pale neck next, his tongue following a dark path towards the place where it met the shoulder. Once there, Watson bit the skin, hard enough to leave a mark, but not enough to break and taste the sweet and powerful blood that obviously run through the other’s veins. The younger Holmes moaned softly and pressed the blond’s head even closer to his body but the man didn’t let him control his actions. Instead moved down, to the well formed chest where he began to lick and kiss the tempting skin that he had thought unattainable not long ago. He would take some sort revenge over Mycroft Holmes for making him believe his partner was an inexperienced virgin and uninterested in sex.

Sherlock decided that he would let his partner have control for a while and let his hands roam John’s body slowly, just making sure to map him, to memorize his figure.

Watson suddenly closed his mouth around a nipple and the brunette just felt the tiniest shadow of his teeth make the contact with the sensitive skin. He arched in pleasure before feeling them come into play along with his tongue.

Now he understood why so many people looked so happy to go on a date and bed him… and he felt even more jealous than ever, now that he was experiencing first-hand what others had enjoyed before.

John seemed to feel the change in the mood because he interrupted his actions to look at him almost concerned.

The younger looking demon took the chance to turn them around once again, and kissed Watson possessively.

“You are mine from now on, John” Sherlock breathed against his lips, before hiding his face in the crook of his neck and biting hard on the soft skin. He didn’t restrain himself in the least and broke the skin there, tasting his partner's blood, savoring the dark, rich flavor. Now, there was no place in the three realms where the blond could hide from him.

Watson arched his back at such action, and his eyes shone with the darkest green. His smile was the biggest, evilest than anyone had ever seen on him, his sharp fangs shinning in the barely lit bedroom. If his lover had been able to see his face just then he would certainly have been impressed by how different it was from the usual calm and kind Doctor Watson he had come to known.

“Just as you are mine” He replied back, his voice rough, before pushing the demon on his back and moving back to his task of tasting and teasing Sherlock’s body.

Slowly he moved downwards, tasting the slightly salted skin. After a little while he raised his head to look at the shining grey orbs of his chosen one.

“Would like to see me get ready for you to take me while I take you in my mouth or would you prefer to do it yourself?” He asked sensuously, letting him know he would like it any way he chose.

The idea of John opening himself for him… it was so strong, so tempting that Sherlock felt his tight control threatening to disappear. Still, this was their first coupling and he wanted to feel Watson’s body under his fingers.

“I’ll do it” He said and this time the green eyed one let him on top at once. They kissed once more before it was the brunette’s turn to kiss the other’s chest, to map the skin with his tongue and slowly reach between his lover’s legs.

“Turn around” He ordered.

The other seemed surprised and raised an eyebrow.

“Demon saliva, John, you can’t get better lube than that” He explained with a knowing smile that made John shiver with desire and acquiesce at once.

Sherlock used his tongue to lick his lover’s most sensitive place while his fingers breached him open, making the blond moan and beg.

“Stop teasing, Sherlock take me! I’m ready!” He assured “Please!” He begged at least, hopping his tone would induce the other to do as he wanted.

The brunette gave a short, playful smack on a round buttock making his partner whimper and moan again. That reaction certainly made the younger Holmes think of some games they would explore in the future.

But right there and then, it was time to move things along. Sherlock licked his own palm until it was wet and applied the moisture on his own shaft. Later, he would ask Watson to do it for him, but for now… he had teased the older looking demon enough, he could feel it in the way he trembled, hear it in the desperation in his voice.

Slowly, he finally began to push against the loosened entrance. John moaned loudly and tried to turn his head to look at the magnificent figure of his lover at his behind him, taking him, making them become one. He finally felt Sherlock still, completely inside of his body and groaned in frustration at being unable to touch him, to run his hands through the other’s back. He wanted to see the brunette, feel even more of him.

“In a moment, John” A rough voice breathed in his ear, while a mouth closed over the center of his nape marking him once again, this time in a more primal way.

The blond yelled in pleasure and the tiniest bit of pain, the sensation proving to be almost too much. He was about to come when he realized there was a strong hand keeping him from reaching orgasm.

“Sherlock!!!” He protested almost desperately.

But the man didn’t say a word, simply releasing the hurt skin and moving slowly out of his partner’s body to help him into the position he wanted. Once they were settled front to front he thrust inside the blond’s body once again, rapidly picking his pace while still effectively blocking him from coming. He wanted to mark his lover inside as he had done outside, to make sure no one would have the least doubt about who John H. Watson belonged to.

The smaller demon moaned and wrapped his legs around Sherlock's waist encouraging him to go even deeper. He wanted to be owned by this magnificent creature he had come to desire and love.

Some minutes later John began to cry and beg to be allowed to come as Sherlock was hitting his pleasure spot with every movement. The younger Holmes licked his lips at the sight the blond made and wondered how bad could be to keep him like that forever, but then realized things were about to reach the point of actual pain for his lover and decided it was time to let him come. He kissed his lover’s red lips while releasing the strong grip. It only took the littlest help for John to orgasm with Sherlock’s name on his lips, that seemed to be the last push to send the brunette over the edge.

 

 

“ _And your brother dared to say you were a blushing virgin!_ ” John said after they had recovered their voices.

“I think that he thought that it would prompt you to try and tempt me into sin…” Sherlock suggested with a smile, remembering he had to back get at his brother for not telling him that John was one of theirs. And yet, to what point he knew for sure was somewhat obscure since he knew that Mycroft was aware of his attraction and his brother had been trying to convince him to choose a mate for ages, which was pretty rich coming from a someone who had spent an eternity without one. They had had lovers, of course, bed partners and pets but never had settled down and now he suspected they were finally about to do just that, if the materializing shadow he had noticed right beside Gregory Lestrade when he was about to teleport him and John was any clue.

“As if I would do such a thing…” John whispered.

“You don’t like making the pure and untainted know the pleasures that only a demon can bring?” Sherlock asked playfully yet curious. Still, under the light tone there was something else, a darker emotion lurking right besides his words.

The blond looked at him for a moment almost surprised by the question.

“I’m not an incubus, Sherlock. I’m…” he began to say but stop suddenly, his green orbs turning a darker green “I was a warrior” John said at last with a sad tone.

Sherlock let his tail come out once again and lifted John's chin with it.

“You still are a warrior, John” The younger Holmes said softly kissing him on the lips “You have just changed battlefield for the moment… but when the time comes, _you’ll be my right hand and the commander of my army_ ” He promised darkly.

**Author's Note:**

> This story is partly result of an old prompt I read somewhere (I have forgotten where since it was years ago, literally), someone asked for a story where John and not Sherlock was the demon, that idea had been on my mind for a while and this is one of the ways I could see it.
> 
> I'm planning to write a second part with Gregory and Mycroft story, but as I have not yet done so I prefer to keep this story as a stand alone. When and if the muse help me to put the next story together I'll add it as a new chapter.
> 
> Feedback is well loved and appreciated. I truly like to know what you think of my stories.
> 
> DISCLAIMER: The characters belong to Conan Doyle and their present incarnation to BBC Networks, the story however is mine.


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